In 2008, when he joined the army, he was a bookish athlete from rugged Idaho with a passion for fencing. A year later, he was a captive of the Afghan Taliban. Today, he is on the way home, a free man at last.

But a new ordeal for Sgt. Bowe Bergdahl, 28, is just beginning.

Held alone for nearly five years, without any contact with fellow soldiers, Bergdahl likely suffered deep psychological scars that could take years to heal, possibly a lifetime, say experts who have studied prisoners held for long periods of time at war.